This project will evaluate whether alternative glycemic markers add value to standard markers (fasting glucose and HbA1c) for long-term prognosis across a wide range of outcomes in a large representative cohort followed for 25-years from midlife to older age. The aims are: 1) To assess the added prognostic value of novel glycemic markers to known measures for identifying populations and subgroups at high risk for microvascular and macrovascular outcomes; 2) To investigate racial- and age-related differences in the associations of glycemic markers with health outcomes; 3) To conduct a genome-wide association study of new glycemic markers to identify susceptibility genes important in glucose metabolism; and 4) To characterize the associations of hypo- and hyper-glycemic states with frailty, mood, and physical and cognitive impairment and dementia risk in the elderly. Design and Methods: We will analyze stored specimens and utilize data from the Atherosclerosis Risk in Communities (ARIC) Study, an ongoing NHLBI-funded community-based epidemiologic cohort of ~15,000 black and white adults followed for 25 years. The proposed research will build on the existing infrastructure of the parent study and utilize blood samples obtained during two phases of the participants' lifespan: during midlife (1990-92, 48-68 years old) and old age (2011-2013, 69-89 years old). The main outcomes of interest are microvascular disease (kidney and retinal disease), macrovascular (cardiovascular) disease, frailty, mood, physical and cognitive impairment, dementia, and all-cause mortality. Significance: If we demonstrate that novel markers of glycemia contribute additional prognostic information, our results will suggest the utility of these measures in clinical practice. Such results would challenge the definition of diabetes. We will also demonstrate whether documented racial disparities and age-related differences in levels of glycemia are clinically important. Our investigation of common genetic determinants will shed light on the biology of diabetes and the mechanisms by which glucose metabolism contributes to the development of complications. If this project is successful, our results will have direct relevance to clinical practice and inform strategies for the prevention of diabetes and its complications.